1. Field of the Invention
The present invention relates to a fuel delivery system and more particularly to a control system for a fuel delivery system for use in gasoline service stations which provides enhanced functionality and diagnostic capabilities heretofore unknown.
2. Description of the Prior Art
Retail fuel delivery systems, for example, for dispensing gasoline, are known to include: one or more underground storage tanks for carrying various grades of fuel; a submersible pump disposed within each of said storage tanks for pumping fuel from the storage tank to a dispenser on demand; a level probe and a tank gauge for monitoring fuel level within the tank; and a dispenser which acts as a point of sale (POS) device for dispensing fuel to consumers. A pump controller is provided to run the submersible pump in response to certain signals being present. For example, many known dispensers include credit card readers for enabling a consumer to charge the purchase at the dispenser and enable the pump. In addition, the pump controller can be enabled from a service station attendant for an unspecified amount of purchase or a specified purchase. When one or more enabling signals are present, the pump controllers are under the control of a trigger mechanism disposed at the dispenser. Examples of such fuel delivery systems are disclosed in: U.S. Pat. Nos. 5,361,216; 5,363,093; 5,376,927; 5,384,714; 5,423,457; 5,757,664 and 6,302,165. Fuel delivery systems are also disclosed in published Patent Application No. U.S. 2001/0037839 A1, as well as commonly-owned U.S. Pat. No. 5,577,895, all hereby incorporated by reference.
Due to regulations promulgated by the Environmental Protection Agency over ten years ago, retail fuel delivery systems are now required to include leak detection systems for detecting leaks in the underground storage tanks. As such, a number of leak detection systems for such underground storage tanks are known. Examples of such leak detection systems are disclosed in U.S. Pat. Nos. 5,363,093; 5,376,927; 5,384,714; 5,423,457; 5,526;679; 5,757,664; and 5,779,097, all hereby incorporated by reference.
Other than the leak detection capabilities, the functional as well as the diagnostic capabilities of such fuel delivery systems are relatively limited. In particular, various common operating conditions exist which either go undiagnosed or are relatively difficult to diagnose. For example, conditions are known in which the submersible pump is installed incorrectly in that it is located too far from the bottom of the tank. This condition is often undiagnosed causing the pump controller to indicate that the tank is empty long before the tank gauge indicates a low level alarm resulting in fuel in the bottom of the tank never being used.
Various conditions are also known to exist which result in false alarms. For example, situations are known in which the pump controller is faulted during a leak detection test. During such a condition, a leak is indicated. False leak detection alarms can also be indicated in fuel delivery systems in which the underground tanks are connected together by piping or are “manifolded” and a check or relief valve is stuck in an open position.
In addition to limited and faulty diagnostics, fuel delivery systems are also known to have relatively limited functionality. For example, when a pump controller is faulted, such faults are indicated on the pump controller itself. As such, service station attendants are known to reset the pump controllers without logging the pump controller fault, thus, losing the fault history. Moreover, the pump controllers are normally contained in locked rooms. Thus, the attendants must be given access to the locked rooms to enable the pump controllers to be manually reset. Thus, there is a need for a control system with enhanced functionality and diagnostic capability for fuel delivery systems.